code: def pretty_format(self, indent=3):
      try:
          accum = "%s:[" % self.label
      except NameError:
          accum = "["
      try:
          accum += "pred '%s'" % (self.pred[0])
      except NameError:
          pass
  
      for feature in sorted(self):
          for item in self[feature]:
              if isinstance(item, FStructure):
                  next_indent = (
                      indent + len(feature) + 3 + len(self.label)
                  )
                  accum += "\n{}{} {}".format(
                      " " * (indent),
                      feature,
                      item.pretty_format(next_indent),
                  )
              elif isinstance(item, tuple):
                  accum += "\n{}{} '{}'".format(
                      " " * (indent), feature, item[0]
                  )
              elif isinstance(item, list):
                  accum += "\n{}{} {{{}}}".format(
                      " " * (indent),
                      feature,
                      (
                          "\n%s" % (" " * (indent + len(feature) + 2))
                      ).join(item),
                  )
              else:  # ERROR
                  raise Exception(
                      "feature %s is not an FStruct, a list, or a tuple"
                      % feature
                  )
      return accum + "]"
  
file_path: nltk/nltk/sem/lfg.py
imports: from itertools import chain
  from nltk.internals import Counter
label_desc: Use image node_id 13 for calling the FStructure obj's underlying member method code with example usage: obj.pretty_format(indent) and returns: unknown